The mobile communications market has been an international bazaar, with a wide variety of equipment to provide different types of networks and services. National telecommunications companies have been deregulated, only to be partially re-regulated to give newly formed competing companies a chance to establish themselves in the marketplace. As a result, diversity of telecommunications equipment has been accelerated. The deregulating process may yield financial benefits to the consumer due to the competitive pressure on price, but they also introduce devices that are sub-optimum and may even delay the realization of the universal mobile telecommunications system ("UMTS").
Mobile communications involve Personal Communications Services ("PCS") that encompass a broad range of services designed to allow people to access public switched telephone networks ("PSTN") regardless of their physical location. As a set of telecommunications features supporting terminal personal and service mobility, PCS will combine many emerging "intelligent network" capabilities of the PSTNs with sophisticated wireless access technologies and related radio network mobility control capabilities. The enormous demand for existing vehicular cellular and residential cordless services demonstrates a widespread public interest in wireless communication and the mobility that it supports. This demand can be expected to grow even more with the evolution to less expensive, lightweight, "pocket-sized" terminals which, combined with various intelligent network services, will provide to the public even greater communications flexibility and portability. Hence, regardless of the many uncertainties, it is reasonable to assume that large segments of the population will eventually have "anytime anywhere" wireless access to PSTNs and services. To plan for this situation, many teletraffic problems will need to be solved.
A major teletraffic problem is equipment incompatibility. A wide variety of equipment from different manufacturers creates a broad spectrum of operational parameters in cellular equipment, causing conflicts between cellular components.
For example, there are different manufacturers of Code Division Multiple Access ("CDMA") mobile stations, such as cellular phones. Mostly, the mobile stations must follow industry standards, such as the "Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System," TIA/EIA/IS-95 ("IS-95"). This standard governs communications between a mobile station and a base transceiver station ("BTS"), but does not address the communication requirements for interaction between a mobile station and cellular telecommunication switch equipment. In this respect, the operational parameters from one manufacturer to another can vary.
Because communication standards are not in place to govern communications between the mobile station and the telecommunication switch components, conflicts arise due to the incompatibility between the mobile station and switch components.
Nevertheless, cellular customers expect to receive service quickly after subscribing. This desire for quick service drives the traditional planning task of ensuring that the network has the necessary equipment in place to anticipate growth and services and to move quickly to capture new market opportunities. Consequently, cellular customers are not content to wait while the trouble is detected and time is further spent correcting the problem.
Complications in cellular communications have arisen due to the use of incompatible Dual-Tone Multi-Frequency ("DTMF") signal sequences (for example, "*33") with subscriber service components. For example, in voice mail services ("VMS"), a cellular customer "dials" a numeric digit on the keypad of their mobile station. Each numeric digit has a unique DTMF signal tone with an "on" duration and an "off" duration. Industry standards have not dictated the duration for these tones. Without a standard, mobile station and service equipment manufacturers may have selected incompatible "on" and "off" durations required for their equipment. Without receiving a compatible "on" and "off" DTMF duration, the VMS cannot be accessed by the cellular customer.
To correct the situation, the cellular customer have had to return their mobile station to a service representative to re-program the DTMF signal durations. Only afterwards would a cellular customer be able to use their mobile station with their subscriber services.
The time needed to correct the problem typically takes longer than a customer would be willing to wait because mobile stations cannot be re-programmed at many of the manufacturer sites. Furthermore, the task of reprogramming all the mobile stations to be compatible with subscriber services is also cost prohibitive to the manufacturer of the mobile station.
Thus, a need exists for normalizing the DTMF tones without the need to reprogram mobile stations, and without having to affect the service provider components.